Here is the best place to get the manifolds. Probably the best price too.
http://www.designengineering.com/catalog/spa-turbo-usa/turbo-manifolds/chevyA T3 will probably work fine on the little 230. I prefer a T4 for 250 and 292. They allow more choices for exh housing and turbine sizes.
Snowman has just done this to his car using a 292 truck manifold and cheap Chinese turbo parts. Worked good till the stock shortblock decided not to play.